Side effects of the contraceptive implant: when to see a doctor

With many different contraceptive methods available, selecting what is best for you can be a daunting decision to make. There is no single contraceptive that suits everyone, and there are many factors to consider when choosing. The contraceptive implant is often chosen by women who want long term contraception and who want to avoid the hassle of remembering to take a pill every day.

The implant is a small plastic rod the size of a matchstick which is inserted under the skin in your upper arm. It contains the hormone progestogen, which is released into your blood circulation slowly and steadily, preventing pregnancy for up to three years from the time of insertion.

As with most hormonal contraceptive methods, the implant exerts its action in several ways. It mainly acts by preventing the release of an egg from the ovary, but it also thickens the cervical mucus, making it difficult for sperm to travel through the cervix. On top of that, it thins the inner lining of the womb, making it harder for an egg to implant on the off chance that it does end up getting fertilised.

With all these mechanisms in action it is believed that the implant is more than 99% effective; less than one woman will get pregnant out of 100 women using the implant.1

As with any form of contraception, there are some risks and side effects to consider. However, these are rarely serious, and should you start experiencing an unwelcome side effect you can have the implant removed at any time. If you are experiencing symptoms that are giving you cause for concern you may wonder if they’re a side effect to be expected, or if something is not right. But what are the side effects, and when is a symptom perhaps a sign you need to see your doctor?

Insertion procedure of the implant, and associated risks

For some, even the very idea of inserting a rod under the skin may seem scary, but it is a simple procedure which only takes minutes and doesn’t require any stitches. A small cut is made on the skin after the area is numbed with a local anaesthetic, and the implant is inserted. You may notice mild bruising and tenderness to touch in the area but it settles within a week or two. However, if it continues to be painful, swollen, warm, and red you may need to consult your doctor as these could be signs of infection, although this is rare.

Irregular periods

One of the most common side effects of the implant is irregular menstrual bleeding, and this is the main reason for early discontinuation of the implant.2 In fact, less than a quarter of women with the implant will continue to have regular periods.3

This change is due to the altered hormone levels in your body with the implant. When you are not using any hormonal contraceptives, the regular menstrual cycle happens due to fluctuating hormone levels in the body, namely oestrogen and progesterone, that rise and fall at specific times of the month.

With the implant, the continuous slow and steady release of progestogen keeps the endometrial lining thin, preventing its overgrowth. Furthermore, disturbance to the normal fall of oestrogen and progestogen levels, which is normally responsible for menstruation, keeps the lining from shedding. These two factors combined often result in less frequent, lighter, or even no bleeding.

Infrequent bleeding is common, with about one third of women having fewer than two episodes of bleeding over a 90 day period and approximately one fifth having no periods at all.

Infrequent bleeding is common, with about one third of women having fewer than two episodes of bleeding over a 90 day period and approximately one fifth having no periods at all.4 However, whether or not your bleeding pattern will change is quite unpredictable, as some women (about one in four) report prolonged or frequent bleeding after the implant.5

This altered bleeding pattern is usually seen within the first three months after insertion of the implant, and often continues to be irregular as long as the implant is in place. Although it may seem worrisome, it is usually not harmful, and shouldn’t be a cause for concern. However, if it is causing you distress, you should go and see your doctor to discuss alternatives.

One instance in which you should see your doctor is if you think you might be pregnant — signs you could be pregnant include no bleeding combined with early signs of pregnancy such as nausea and breast tenderness. However, none of these are conclusive, so it is best to take a simple pregnancy test if you are in doubt. On top of this, if your bleeding gets particularly heavy, or your bleeding pattern suddenly changes, it is important to see your doctor as it may be a symptom of another condition such as fibroids or uterine polyps.

Temporary side effects following insertion of the implant

Unlike irregular periods which tend to persist, many short lasting effects such as headache, dizziness, and nausea have been reported after insertion of the implant, often appearing within a week or two. Headaches are reported quite commonly, either as a new occurrence, or as a change to an existing headache pattern.

Fluctuating levels of hormones, mainly oestrogen and progesterone, are known to interact with brain chemicals such as glutamate, and are associated with headaches. This is the cause of the ‘menstrual migraines’ that many women experience shortly before or during menstruation. The same interaction may be behind the headaches following implant insertion too, but as of yet research has failed to establish a causal relationship between the two.

These symptoms are temporary and often settle after a few months as your hormone levels stabilise. Until then, simple painkillers can help. However, if they are severe, and seem to be continuous, you should see your GP for advice.

Some women complain of having low mood or mood swings after implant insertion. Effects of progestogen on brain chemicals which affect the mood, such as serotonin and glutamate may play a role, but this isn’t yet scientifically proven.

Breast pain and tenderness is another common complaint following implant insertion. This is a result of stretching of ligaments in the breast, which occurs with the progestogen induced enlargement of the breast glands. This complaint is also temporary, and if it affects you it should gradually reduce within a few months as progestogen levels stabilise.

Some women complain of having low mood or mood swings after implant insertion. Effects of progestogen on brain chemicals which affect the mood, such as serotonin and glutamate may play a role, but this isn’t yet scientifically proven. These mood swings often settle with time, but you need to seek medical advice if your low mood is persistent, or severe and affects your daily life.

What are other common side effects and should I be worried?

Weight gain following implant insertion is commonly reported and often a major concern for women thinking of getting the implant. However, there is no scientific evidence suggesting a causal relationship between the two.6 It is different for every person, and unfortunately you cannot predict how your weight will be affected as lots of other factors, such as diet, lifestyle, genetic predisposition, and other medical conditions play a role as well.

Some women complain of worsening of acne following insertion of the implant. This may be due to change of the oestrogen to progestogen balance in the body. Progestogen is known to increase the production of sebum (oily secretion from sebaceous glands), and this, in excess, may block hair follicles, leading to acne. Contradictory to this theory, however, is that some people report their acne improving after insertion of the implant.7 If acne or weight gain is causing you distress and you believe it is linked to the implant, then visit your doctor to discuss your options.

What are the risks associated with the implant, and who should avoid it?

Being a progestogen only contraceptive method, the implant has the advantage of being able to be used in conditions where oestrogen needs to be avoided, including when someone is breastfeeding, and in the presence of cardiovascular risk factors. However, there are certain conditions where the implant is contraindicated, or better avoided due to the health risks it presents outweighing its benefits.

For example, the implant is not recommended if you have unexplained vaginal bleeding as the menstrual irregularities it causes may mask the symptoms of an underlying condition.8 You should also avoid the implant if you have breast cancer, as it (along with any other hormonal contraceptive) can affect the prognosis due to the cancer being hormonally sensitive.9

Although there is no definitive evidence concluding that the implant increases the risk of blood clots, it is not recommended in those who have had a stroke, are at increased risk of having a stroke, or who have ischemic heart disease.10

Progestogen is metabolised in the liver, so needs to be avoided in conditions with altered liver functions, such as severe cirrhosis and certain liver tumours, as the efficacy of the implant will be affected. Also, drugs which induce enzymes such as anti-epileptics, rifampicin, and griseofulvin may lead to lower progesterone concentration in the blood, causing contraceptive failure.

So, if you are already on any long term medications, always discuss this with your doctor before deciding on a contraceptive method. It is best, too, to get medical advice prior to implant insertion if you have any comorbidities such as diabetes, high blood pressure, kidney disease, headaches, or history of depression.

When should you seek immediate medical advice while on the implant?

Although current evidence shows little or no increased risk of blood clots with the use of the implant, it is a topic on which more research needs to be done. So, see your doctor immediately if you experience any alarming symptoms such as severe chest pain, sudden difficulty breathing, severe persistent leg pain, sudden severe headaches, weakness, or numbness.

If you think you might be pregnant, and on top of that if you develop severe lower abdominal pain with or without bleeding, go to your doctor immediately as the possibility of an ectopic pregnancy needs to be excluded. You also need to seek medical care if you are no longer able to feel the implant under your skin, or if you can feel it but it seems to be broken or bent.

Finally, if you have the implant and are worried about any symptom at all that you have been experiencing following its insertion, going to your nearest sexual health clinic or discussing the problem with your GP as soon as possible is advisable.

Featured image shows a woman taking a sip out of a mug. The image is cropped so you can only see the lower part of her face and her hands holding the mug.

Shehara graduated from the University of Colombo, with degrees in Medicine and Surgery. She has research experience in various fields of medicine, having worked at the Epidemiology Unit of Sri Lanka and National Institute of Infectious Diseases. She is currently practising paediatrics and radiology at the Lady Ridgeway Hospital, Colombo, the main paediatric hospital in the country. Though a medical doctor in profession, writing has always been her passion and she hopes her articles will help empower women.